This is a CD-ROM full of Apple Macintosh software from 1988. This is the PD ROM Volume I from the BMUG (Berkeley Macintosh Users Group). It was published by Discovery Systems.
The disc was ripped using ImgBurn and produced errors at 99% of the read, although the disc was clean and this is probably only a weird format being read from such an early disc. The disc image (.iso) mounts perfectly in a Macintosh emulator like Basilisk II.
From the back of the disc case: The BMUG CD-ROM (publicly distributable CD-ROM) includes over 250 megabytes of the finest public domain, ShareWare, and free software, clip art and international bulletin board threads available for the Macintosh. Secured and tested by BMUG, you can be assured that the PD ROM contains the most current and highest quality programs available.